lm75.c

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/*
 * lm75.c - Part of lm_sensors, Linux kernel modules for hardware
 *   monitoring
 * Copyright (c) 1998, 1999  Frodo Looijaard <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include "lm75.h"


/*
 * This driver handles the LM75 and compatible digital temperature sensors.
 */

enum lm75_type {        /* keep sorted in alphabetical order */
    adt75,
    ds1775,
    ds75,
    lm75,
    lm75a,
    max6625,
    max6626,
    mcp980x,
    stds75,
    tcn75,
    tmp100,
    tmp101,
    tmp105,
    tmp175,
    tmp275,
    tmp75,
};

/* Addresses scanned */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
                    0x4d, 0x4e, 0x4f, I2C_CLIENT_END };


/* The LM75 registers */
#define LM75_REG_CONF       0x01
static const u8 LM75_REG_TEMP[3] = {
    0x00,       /* input */
    0x03,       /* max */
    0x02,       /* hyst */
};

/* Each client has this additional data */
struct lm75_data {
    struct device       *hwmon_dev;
    struct mutex        update_lock;
    u8          orig_conf;
    char            valid;      /* !=0 if registers are valid */
    unsigned long       last_updated;   /* In jiffies */
    u16         temp[3];    /* Register values,
                           0 = input
                           1 = max
                           2 = hyst */
};

static int lm75_read_value(struct i2c_client *client, u8 reg);
static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
static struct lm75_data *lm75_update_device(struct device *dev);


/*-----------------------------------------------------------------------*/

/* sysfs attributes for hwmon */

static ssize_t show_temp(struct device *dev, struct device_attribute *da,
             char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
    struct lm75_data *data = lm75_update_device(dev);

    if (IS_ERR(data))
        return PTR_ERR(data);

    return sprintf(buf, "%d\n",
               LM75_TEMP_FROM_REG(data->temp[attr->index]));
}

static ssize_t set_temp(struct device *dev, struct device_attribute *da,
            const char *buf, size_t count)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
    struct i2c_client *client = to_i2c_client(dev);
    struct lm75_data *data = i2c_get_clientdata(client);
    int nr = attr->index;
    long temp;
    int error;

    error = kstrtol(buf, 10, &temp);
    if (error)
        return error;

    mutex_lock(&data->update_lock);
    data->temp[nr] = LM75_TEMP_TO_REG(temp);
    lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
    mutex_unlock(&data->update_lock);
    return count;
}

static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
            show_temp, set_temp, 1);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
            show_temp, set_temp, 2);
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);

static struct attribute *lm75_attributes[] = {
    &sensor_dev_attr_temp1_input.dev_attr.attr,
    &sensor_dev_attr_temp1_max.dev_attr.attr,
    &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,

    NULL
};

static const struct attribute_group lm75_group = {
    .attrs = lm75_attributes,
};

/*-----------------------------------------------------------------------*/

/* device probe and removal */

static int
lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
    struct lm75_data *data;
    int status;
    u8 set_mask, clr_mask;
    int new;

    if (!i2c_check_functionality(client->adapter,
            I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
        return -EIO;

    data = devm_kzalloc(&client->dev, sizeof(struct lm75_data), GFP_KERNEL);
    if (!data)
        return -ENOMEM;

    i2c_set_clientdata(client, data);
    mutex_init(&data->update_lock);

    /* Set to LM75 resolution (9 bits, 1/2 degree C) and range.
     * Then tweak to be more precise when appropriate.
     */
    set_mask = 0;
    clr_mask = (1 << 0)         /* continuous conversions */
        | (1 << 6) | (1 << 5);      /* 9-bit mode */

    /* configure as specified */
    status = lm75_read_value(client, LM75_REG_CONF);
    if (status < 0) {
        dev_dbg(&client->dev, "Can't read config? %d\n", status);
        return status;
    }
    data->orig_conf = status;
    new = status & ~clr_mask;
    new |= set_mask;
    if (status != new)
        lm75_write_value(client, LM75_REG_CONF, new);
    dev_dbg(&client->dev, "Config %02x\n", new);

    /* Register sysfs hooks */
    status = sysfs_create_group(&client->dev.kobj, &lm75_group);
    if (status)
        return status;

    data->hwmon_dev = hwmon_device_register(&client->dev);
    if (IS_ERR(data->hwmon_dev)) {
        status = PTR_ERR(data->hwmon_dev);
        goto exit_remove;
    }

    dev_info(&client->dev, "%s: sensor '%s'\n",
         dev_name(data->hwmon_dev), client->name);

    return 0;

exit_remove:
    sysfs_remove_group(&client->dev.kobj, &lm75_group);
    return status;
}

static int lm75_remove(struct i2c_client *client)
{
    struct lm75_data *data = i2c_get_clientdata(client);

    hwmon_device_unregister(data->hwmon_dev);
    sysfs_remove_group(&client->dev.kobj, &lm75_group);
    lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
    return 0;
}

static const struct i2c_device_id lm75_ids[] = {
    { "adt75", adt75, },
    { "ds1775", ds1775, },
    { "ds75", ds75, },
    { "lm75", lm75, },
    { "lm75a", lm75a, },
    { "max6625", max6625, },
    { "max6626", max6626, },
    { "mcp980x", mcp980x, },
    { "stds75", stds75, },
    { "tcn75", tcn75, },
    { "tmp100", tmp100, },
    { "tmp101", tmp101, },
    { "tmp105", tmp105, },
    { "tmp175", tmp175, },
    { "tmp275", tmp275, },
    { "tmp75", tmp75, },
    { /* LIST END */ }
};
MODULE_DEVICE_TABLE(i2c, lm75_ids);

#define LM75A_ID 0xA1

/* Return 0 if detection is successful, -ENODEV otherwise */
static int lm75_detect(struct i2c_client *new_client,
               struct i2c_board_info *info)
{
    struct i2c_adapter *adapter = new_client->adapter;
    int i;
    int conf, hyst, os;
    bool is_lm75a = 0;

    if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
                     I2C_FUNC_SMBUS_WORD_DATA))
        return -ENODEV;

    /*
     * Now, we do the remaining detection. There is no identification-
     * dedicated register so we have to rely on several tricks:
     * unused bits, registers cycling over 8-address boundaries,
     * addresses 0x04-0x07 returning the last read value.
     * The cycling+unused addresses combination is not tested,
     * since it would significantly slow the detection down and would
     * hardly add any value.
     *
     * The National Semiconductor LM75A is different than earlier
     * LM75s.  It has an ID byte of 0xaX (where X is the chip
     * revision, with 1 being the only revision in existence) in
     * register 7, and unused registers return 0xff rather than the
     * last read value.
     *
     * Note that this function only detects the original National
     * Semiconductor LM75 and the LM75A. Clones from other vendors
     * aren't detected, on purpose, because they are typically never
     * found on PC hardware. They are found on embedded designs where
     * they can be instantiated explicitly so detection is not needed.
     * The absence of identification registers on all these clones
     * would make their exhaustive detection very difficult and weak,
     * and odds are that the driver would bind to unsupported devices.
     */

    /* Unused bits */
    conf = i2c_smbus_read_byte_data(new_client, 1);
    if (conf & 0xe0)
        return -ENODEV;

    /* First check for LM75A */
    if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) {
        /* LM75A returns 0xff on unused registers so
           just to be sure we check for that too. */
        if (i2c_smbus_read_byte_data(new_client, 4) != 0xff
         || i2c_smbus_read_byte_data(new_client, 5) != 0xff
         || i2c_smbus_read_byte_data(new_client, 6) != 0xff)
            return -ENODEV;
        is_lm75a = 1;
        hyst = i2c_smbus_read_byte_data(new_client, 2);
        os = i2c_smbus_read_byte_data(new_client, 3);
    } else { /* Traditional style LM75 detection */
        /* Unused addresses */
        hyst = i2c_smbus_read_byte_data(new_client, 2);
        if (i2c_smbus_read_byte_data(new_client, 4) != hyst
         || i2c_smbus_read_byte_data(new_client, 5) != hyst
         || i2c_smbus_read_byte_data(new_client, 6) != hyst
         || i2c_smbus_read_byte_data(new_client, 7) != hyst)
            return -ENODEV;
        os = i2c_smbus_read_byte_data(new_client, 3);
        if (i2c_smbus_read_byte_data(new_client, 4) != os
         || i2c_smbus_read_byte_data(new_client, 5) != os
         || i2c_smbus_read_byte_data(new_client, 6) != os
         || i2c_smbus_read_byte_data(new_client, 7) != os)
            return -ENODEV;
    }

    /* Addresses cycling */
    for (i = 8; i <= 248; i += 40) {
        if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
         || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
         || i2c_smbus_read_byte_data(new_client, i + 3) != os)
            return -ENODEV;
        if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7)
                != LM75A_ID)
            return -ENODEV;
    }

    strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE);

    return 0;
}

#ifdef CONFIG_PM
static int lm75_suspend(struct device *dev)
{
    int status;
    struct i2c_client *client = to_i2c_client(dev);
    status = lm75_read_value(client, LM75_REG_CONF);
    if (status < 0) {
        dev_dbg(&client->dev, "Can't read config? %d\n", status);
        return status;
    }
    status = status | LM75_SHUTDOWN;
    lm75_write_value(client, LM75_REG_CONF, status);
    return 0;
}

static int lm75_resume(struct device *dev)
{
    int status;
    struct i2c_client *client = to_i2c_client(dev);
    status = lm75_read_value(client, LM75_REG_CONF);
    if (status < 0) {
        dev_dbg(&client->dev, "Can't read config? %d\n", status);
        return status;
    }
    status = status & ~LM75_SHUTDOWN;
    lm75_write_value(client, LM75_REG_CONF, status);
    return 0;
}

static const struct dev_pm_ops lm75_dev_pm_ops = {
    .suspend    = lm75_suspend,
    .resume     = lm75_resume,
};
#define LM75_DEV_PM_OPS (&lm75_dev_pm_ops)
#else
#define LM75_DEV_PM_OPS NULL
#endif /* CONFIG_PM */

static struct i2c_driver lm75_driver = {
    .class      = I2C_CLASS_HWMON,
    .driver = {
        .name   = "lm75",
        .pm = LM75_DEV_PM_OPS,
    },
    .probe      = lm75_probe,
    .remove     = lm75_remove,
    .id_table   = lm75_ids,
    .detect     = lm75_detect,
    .address_list   = normal_i2c,
};

/*-----------------------------------------------------------------------*/

/* register access */

/*
 * All registers are word-sized, except for the configuration register.
 * LM75 uses a high-byte first convention, which is exactly opposite to
 * the SMBus standard.
 */
static int lm75_read_value(struct i2c_client *client, u8 reg)
{
    if (reg == LM75_REG_CONF)
        return i2c_smbus_read_byte_data(client, reg);
    else
        return i2c_smbus_read_word_swapped(client, reg);
}

static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
{
    if (reg == LM75_REG_CONF)
        return i2c_smbus_write_byte_data(client, reg, value);
    else
        return i2c_smbus_write_word_swapped(client, reg, value);
}

static struct lm75_data *lm75_update_device(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct lm75_data *data = i2c_get_clientdata(client);
    struct lm75_data *ret = data;

    mutex_lock(&data->update_lock);

    if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
        || !data->valid) {
        int i;
        dev_dbg(&client->dev, "Starting lm75 update\n");

        for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
            int status;

            status = lm75_read_value(client, LM75_REG_TEMP[i]);
            if (unlikely(status < 0)) {
                dev_dbg(dev,
                    "LM75: Failed to read value: reg %d, error %d\n",
                    LM75_REG_TEMP[i], status);
                ret = ERR_PTR(status);
                data->valid = 0;
                goto abort;
            }
            data->temp[i] = status;
        }
        data->last_updated = jiffies;
        data->valid = 1;
    }

abort:
    mutex_unlock(&data->update_lock);
    return ret;
}

module_i2c_driver(lm75_driver);

MODULE_AUTHOR("Frodo Looijaard <[email protected]>");
MODULE_DESCRIPTION("LM75 driver");
MODULE_LICENSE("GPL");